Okay. But many clients implement NIP10 like that - Snort, Primal, Satellite & maybe Damus?

Also, checked on Amethyst, if I reply to a note mentioning another, the replied to note is in first "e" tag and the mention is 2nd. Is this how it's supposed to work?

In any case, since it looks like changes to any client will lead to breaking flow of threads of the old notes in some client, and this happens only in reply + note mentions, I should probably let it go (&pray NIP-27 & marked tags becomes commonplace)

Thanks for explaining & helping me understand Vitor!